1. Field of the Invention
This invention relates to antennas. More specifically, this invention relates to dielectric rod antennas.
While the present invention is described herein with reference to a particular embodiment, it is understood that the invention is not limited thereto. Those having ordinary skill in the art and access to the teachings provided herein will recognize additional embodiments within the scope thereof.
2. Description of the Related Art
Many satellites include a "telemetry and command" antenna system for facilitating communication with an earth station. Such antenna systems often include two cones and project a beam having a longitudinal axis coincident with that of the satellite. Spin stabilized satellites are stabilized by rotating about their longitudinal axes. Accordingly, telemetry and command antennas are generally omnidirectional. Omnidirectional antennas are disposed to receive signals from any direction provided such signals are within the field of view of the antenna. The field of view of the antenna is quantified by reference to its "elevation angle"--the angle subtended by the projected antenna beam relative to the longitudinal axis. Conventional dual cone antenna systems are typically characterized by an elevation angle of less than .+-.90 degrees. The breadth of the elevation angle of a satellite's telemetry and command antenna influences the permissible range of orientations the satellite may assume relative to the earth without impairing communication therewith. Accordingly, a need in the art exists for an antenna adapted for telemetry and command communication which has an elevation angle in excess of .+-.90 degrees.
Existing satellite telemetry and command antennas also have relatively narrow bandwidths. In particular, the spectrum of frequencies conventionally available for communication is generally equivalent to two percent of the center frequency of the antenna. This narrow bandwidth generally necessitates the deployment of separate antennas for transmit and receive channels in order to avoid interference therebetween.
It follows that a need in the art exists for a satellite antenna having a bandwidth sufficient to simultaneously accommodate transmit and receive channels while maintaining adequate interchannel isolation.